A terminal locking structure for locking a terminal in a terminal accommodation chamber of a connector housing, the terminal locking structure comprises: a locking lance configured to lock the terminal to prevent the terminal from coming off from the terminal accommodation chamber, the locking lance being bendable in a direction intersecting the insertion direction of the terminal into the terminal accommodation chamber; and a flexible arm bendable in the direction intersecting the insertion direction of the terminal into the terminal accommodation chamber together with the locking lance, the flexible arm being formed extending from a front end of the locking lance to the insertion opening side provided for a corresponding terminal in the terminal accommodation chamber and being connected to an inner wall of the terminal accommodation chamber.